Cleaning composition and methods thereof

BACKGROUND

0001The electronics industry has experienced an ever increasing demand for smaller and faster electronic devices which are simultaneously able to support a greater number of increasingly complex and sophisticated functions. Accordingly, there is a continuing trend in the semiconductor industry to manufacture low-cost, high-performance, and low-power integrated circuits (ICs). Thus far these goals have been achieved in large part by scaling down semiconductor IC dimensions (e.g., minimum feature size) and thereby improving production efficiency and lowering associated costs. However, such scaling has also introduced increased complexity to the semiconductor manufacturing process. Thus, the realization of continued advances in semiconductor ICs and devices calls for similar advances in semiconductor manufacturing processes and technology.

0002As merely one example, semiconductor lithography processes may be used to optically transfer patterns (e.g., using a photomask or reticle) onto a substrate. For instance, in various lithography processes, a resist film is spin-coated onto a surface of a wafer and is subsequently exposed and developed to form a pattern that can be transferred to the wafer (e.g., by a subsequent etching process). With the continued scaling down of IC dimensions, there has been a demand for a reduction in resist film thickness as well as resist materials offering improved reflectivity control, substrate planarization, adhesion promotion, chemical matching, and protection from contamination. Accordingly, various new resist materials and processes have been developed. For example, some lithography processes may employ a silicon-containing resist over a bottom anti-reflective coating (BARC) layer to reduce resist film thickness. In addition, some lithography processes use a tri-layer stack that includes a resist over a silicon-containing BARC layer over an organic underlayer. However, these approaches present new challenges.

0003For example, the silicon-containing material used in such processes may form a hardened gel by forming cros slinks therein, for example, when solvents of the silicon-containing material dry out. Moreover, the equipment that handles such material must undergo frequent cleaning processes to avoid becoming clogged or otherwise contaminated, and to avoid defect formation on production wafers processed by such equipment. Thus, existing techniques have not proved entirely satisfactory in all respects.

BRIEF DESCRIPTION OF THE DRAWINGS

0004Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

0005<figref idref="DRAWINGS">FIG. 1</figref> illustrates a silicon-containing material cross-linking reaction, in accordance with some embodiments;

0006<figref idref="DRAWINGS">FIG. 2A</figref> illustrates an ineffectiveness of using existing cleaning solutions to remove a silicon-containing hard mask material;

0007<figref idref="DRAWINGS">FIG. 2B</figref> illustrates the effects of pH in the colloidal silica-water system, in accordance with various embodiments;

0008<figref idref="DRAWINGS">FIG. 3A</figref> illustrates a semiconductor system that may benefit from various aspects of the present disclosure;

0009<figref idref="DRAWINGS">FIGS. 3B and 3C</figref> illustrate components of the system of <figref idref="DRAWINGS">FIG. 3A</figref> being cleaned by a cleaning solution, according to various aspects of the present disclosure;

0010<figref idref="DRAWINGS">FIG. 4</figref> illustrates an alternative method of cleaning components of the system of <figref idref="DRAWINGS">FIG. 3A</figref>, according to various aspects of the present disclosure;

0011<figref idref="DRAWINGS">FIG. 5</figref> illustrates a reaction where bonds in a cross-linked silicon-containing material are broken, in accordance with some embodiments;

0012<figref idref="DRAWINGS">FIG. 6</figref> illustrates an effectiveness of various embodiments of a cleaning solution to remove a silicon-containing hard mask material;

0013<figref idref="DRAWINGS">FIGS. 7A and 7B</figref> illustrate a flow chart of a semiconductor manufacturing process, in accordance with some embodiments; and

0014<figref idref="DRAWINGS">FIGS. 8A-8G</figref> illustrate a substrate at various stages of the semiconductor manufacturing process of <figref idref="DRAWINGS">FIGS. 7A and 7B</figref>, in accordance with some embodiments.

DETAILED DESCRIPTION

0015The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

0016Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

0017The present disclosure is generally related to cleaning solution compositions and their applications. The cleaning solution can be used to clean semiconductor fabrication equipment, especially the apparatuses for delivering, dispensing, and collecting silicon-containing material in lithography spin-coating processes. The cleaning solution can also be used to remove a silicon-containing hard mask after the hard mask has been used in etching processes.

0018In a typical lithography patterning process, a resist layer is formed over a hard mask layer and is patterned with an IC design layout. An etching process is subsequently followed, which etches the hard mask layer using the patterned resist layer as an etch mask, thereby transferring the pattern to the hard mask layer. Further steps are performed to transfer the pattern to a substrate. As IC dimensions continue to scale down, resist layers have also scaled down, presenting new challenges. In some examples, the resist pattern has become narrower and taller, where such high aspect ratios cause the resist pattern to easily collapse. Additionally, as resist layer thicknesses have decreased, there may not be a sufficient thickness of resist to adequately transfer a resist pattern to an underlying layer. In some aspects, this may be due to an insufficient etching resistance of the resist layer.

0019Silicon-containing materials, implemented in bilayer and multilayer (e.g., tri-layer) processes, have been used in an effort to successfully implement thin imaging layers which overcome one or more of the problems noted above (e.g., pattern collapse, insufficient etching resistance, etc.). In the bilayer approach, a silicon-containing resist layer may be formed over a BARC layer. The silicon-containing resist has a higher etch resistance than conventional resists and therefore needs not be as thick as conventional resists. In the multilayer or tri-layer approach, a thin resist layer may be formed over a silicon-containing BARC (or hard mask) layer which is in turn formed over an underlying BARC layer. In some embodiments, the silicon-containing BARC layer may be formed over an organic underlayer such as a spin-on carbon underlayer. The thin resist layer may be used to pattern the silicon-containing BARC layer, which is then used to pattern the underlying BARC layer. In various embodiments, all three layers (i.e., resist, silicon-containing BARC, and underlying BARC) may be formed using a spin-coating process or a chemical vapor deposition (CVD) process.

0020Both the bilayer and multilayer approach take advantage of the high density of the silicon-containing materials used therein, which is a result of a cross-linking capability of their constituent monomers and molecules. With reference to the example of <figref idref="DRAWINGS">FIG. 1</figref>, silicon-containing materials used in the bilayer or multilayer processes described above may include monomers such as monomer <b>102</b> which includes Si bonded to OR₁groups, where O is oxygen and R₁includes an organic substituent such as methyl, ethyl, or aryl. Monomers of the silicon-containing material (e.g., the monomer <b>102</b>) are very unstable and constituent OR₁groups may readily hydrolyze, resulting in monomers such as monomer <b>104</b> where a hydroxyl group is formed in place of an OR₁group. Monomers <b>102</b>, <b>104</b> may then react to form a cross-linked structure such as cross-linked structure <b>106</b>. In various examples, the hydrolysis and cross-linking described above will readily occur when solvents of the silicon-containing materials dry out.

0021However, the same property that makes these silicon-containing materials desirable for lithography processes also presents a challenge to lithography equipment handling these materials. For example, cross-linked silicon-containing material may coat surfaces of containers that store such silicon-containing materials, as well as pipelines and delivery apparatuses that deliver the materials in liquid form (e.g., during spin-coating processes), and collection apparatuses that collect waste materials (e.g., during spin-coating processes). In order to avoid defect formation on production wafers processed by such contaminated equipment, the equipment needs to be regularly and effectively cleaned to remove the silicon-containing material from the surfaces of the processing equipment. To illustrate the difficulty in removing such silicon-containing material (e.g., from surfaces of lithography equipment), <figref idref="DRAWINGS">FIG. 2A</figref> illustrates film thickness (FT) versus delay time (in hours) for a plurality of silicon-containing hard mask materials. “Delay time”, as used herein, refers to an amount of time that elapses prior to application of a rinsing/cleaning agent used to remove the silicon-containing material. For the example of <figref idref="DRAWINGS">FIG. 2A</figref>, the rinsing/cleaning agent includes a traditional cleaning solvent, such as OK73 (70% Propylene glycol monomethylether+30% Propylene glycol monomethylether acetate). By way of example, two particular silicon-containing hard mask materials, ML<b>1</b> and ML<b>2</b>, are labeled in <figref idref="DRAWINGS">FIG. 2A</figref>. For the case of ML<b>1</b>, curve <b>102</b> shows that the ML<b>1</b> material layer will retain over 80% of its as-deposited thickness even when OK73 is immediately applied (i.e., zero delay time) and will become nearly impossible to remove by OK73 after about half an hour delay. For the case of ML<b>2</b>, curve <b>104</b> shows that the ML<b>2</b> material layer is easier to remove than the ML<b>1</b> material layer, but becomes increasingly difficult to remove by OK73 as time passes. Consequently, the lithography equipment handling these materials may become clogged as the materials harden. Furthermore, the material may form particles that contaminate wafers during various processing stages.

0022It is therefore an objective of the present disclosure to provide new cleaning compositions that can effectively remove such silicon-containing materials (e.g., from lithography equipment surfaces). In the various embodiments described herein, formation of a hardened silicon-containing material layer may occur in accordance with a sol-gel process, where a ‘sol’ (i.e., solution, such as silicon-containing liquid <b>310</b>) evolves into a gel, for example, when solvents of the silicon-containing material dry out. By way of example, and with reference to <figref idref="DRAWINGS">FIG. 2B</figref>, illustrated therein is a graph showing the effects of pH in the colloidal silica-water system. <figref idref="DRAWINGS">FIG. 2B</figref> is taken from R. K. Iler, The Chemistry of Silica, Wiley, New York, 1979, the contents of which are herein incorporated by reference. As illustrated in <figref idref="DRAWINGS">FIG. 2B</figref>, at a pH value of about 8-10, condensation increases, leading to the formation of a stable gel or non-dissolving polymer. At a pH value greater than about 10, a hydrolysis reaction is preferred, and an increased negative charge (e.g., provided by hydroxide ions of the cleaning solution) retards the formation of gel or particles. Thus, by way of example, a hardened silicon-containing material, as described herein, may become unstable (and thus dissolve) at pH values greater than about 10 due to the presence of the increased negative charge.

0023Now, referring to <figref idref="DRAWINGS">FIG. 3A</figref>, shown therein is a semiconductor spin-coating system <b>300</b> that may benefit from various aspects of the present disclosure. As shown, the system <b>300</b> includes a substrate stage <b>302</b> designed to retain a substrate <b>304</b> to be patterned. The substrate <b>304</b> is coated with a silicon-containing material layer <b>306</b>, for example, as part of a bilayer or multilayer lithography stack as described above. The substrate stage <b>302</b> is operable to spin such that the substrate <b>304</b> secured thereon is spun accordingly during the spin-coating process. The substrate stage <b>302</b> includes a mechanism, such as vacuum suction mechanism, electrostatic chucking mechanism, or other suitable mechanism, to secure the substrate <b>304</b>. In the present embodiments, the substrate <b>304</b> is a semiconductor wafer, such as a silicon wafer. In some embodiments, the substrate <b>304</b> may include various layers, including conductive or insulating layers formed on a semiconductor substrate. The substrate <b>304</b> may include various doping configurations depending on design requirements as is known in the art. The substrate <b>304</b> may also include other semiconductors such as germanium, silicon carbide (SiC), silicon germanium (SiGe), or diamond. Alternatively, the substrate <b>304</b> may include a compound semiconductor and/or an alloy semiconductor. Further, the substrate <b>304</b> may optionally include an epitaxial layer (epi-layer), may be strained for performance enhancement, may include a silicon-on-insulator (SOI) structure, and/or have other suitable enhancement features.

0024The system <b>300</b> further includes a drive shaft <b>308</b> coupled to the substrate stage <b>302</b> and that is operable to drive the substrate stage <b>302</b> and the substrate <b>304</b> secured thereon in various modes. In particular, the drive shaft <b>308</b> may be coupled to a motor that serves to spin the drive shaft <b>308</b>, as indicated by arrow <b>309</b>, and thereby rotate the substrate stage <b>302</b> and the substrate <b>304</b> at various spin speeds in accordance with various modes of operation (e.g., such as coating and rinsing). In some embodiments, the drive shaft <b>308</b> is further coupled to an elevation module that serves to move the substrate stage <b>302</b> and the substrate <b>304</b> along a vertical direction so that the substrate <b>304</b> may be positioned at a lower or higher level.

0025In various examples, a silicon-containing liquid <b>310</b> is dispensed through a nozzle <b>312</b> over the substrate <b>304</b> while it is spun. As solvents in the liquid <b>310</b> dry out, the silicon-containing material layer <b>306</b> is formed. The silicon-containing liquid <b>310</b> is stored in a container <b>314</b> and is delivered to the nozzle <b>312</b> through a delivery apparatus <b>316</b> that includes a pipeline <b>318</b>. In the embodiment as shown, a pressurized gas <b>320</b>, such as nitrogen, may be introduced into the container <b>314</b> to force the liquid <b>310</b> into the delivery apparatus <b>316</b>. The system <b>300</b> further includes a container <b>322</b> that holds a cleaning solution <b>324</b> which will be described in more details below. In the embodiment as shown, a pressurized gas <b>326</b>, such as nitrogen, may be introduced into the container <b>322</b> to force the cleaning solution <b>324</b> into the delivery apparatus <b>316</b>. In various embodiments, the delivery apparatus <b>316</b> includes a three-way valve <b>328</b> that alternately directs the silicon-containing liquid <b>310</b> to the pipeline <b>318</b> (e.g., during spin-coating cycles) or directs the cleaning solution <b>324</b> to the pipeline <b>318</b> (e.g., during cleaning cycles). In various embodiments, the delivery apparatus <b>316</b> may alternatively use a pump or other mechanism in delivering the liquid <b>310</b> and the cleaning solution <b>324</b> to the pipeline <b>318</b> of the delivery apparatus <b>316</b>.

0026The system <b>300</b> further includes a waste collection apparatus <b>330</b> that includes a cup <b>332</b> and a drain <b>334</b>. The cup <b>332</b> is configured to at least partially enclose the substrate stage <b>302</b>, as shown in <figref idref="DRAWINGS">FIG. 3A</figref>, to effectively catch the liquid <b>310</b> spun off from the substrate <b>304</b> (e.g., during the spin-coating process). In some embodiments, the cup <b>332</b> is designed to have a cylindrical structure. In some embodiments, the cup <b>332</b> is integrated with the drain <b>334</b> such that the liquid captured by the cup <b>332</b> is sent out through the drain <b>334</b> for further processing.

0027As described above, the various components of the delivery apparatus <b>316</b> and the waste collection apparatus <b>330</b> could become clogged by the silicon-containing material <b>310</b> as it deposits onto the surfaces of the various components. Hence, the system <b>300</b> periodically undergoes cleaning cycles to remove such deposits. With reference to the example of <figref idref="DRAWINGS">FIG. 3B</figref>, illustrated therein are some components of the system <b>300</b> being cleaned in one such cleaning cycle. In the illustration of <figref idref="DRAWINGS">FIG. 3B</figref>, the substrate <b>304</b> including the silicon-containing material layer <b>306</b> have been removed to undergo further processing, such as exposing and developing, which are not illustrated here. The nozzle <b>312</b> has been repositioned to direct any fluid to a waste collection apparatus <b>330</b>A including a drain <b>334</b>A. Further, the three-way valve <b>328</b> is configured to switch off flow of the liquid <b>310</b> and switch on flow of the cleaning solution <b>324</b>. The pressurized gas <b>326</b>, such as nitrogen, is introduced to the container <b>322</b> to force the cleaning solution <b>324</b> into the delivery apparatus <b>316</b>. The cleaning solution <b>324</b> flushes (i.e., cleans) surfaces of the delivery apparatus <b>316</b> including the pipeline <b>318</b> and the nozzle <b>312</b>, and any waste is collected by the waste collection apparatus <b>330</b>A and is sent out through the drain <b>334</b>A. It is noted that the various components may be cleaned without being taken out of the spin-coating system <b>300</b>, thereby reducing the system's off-line time. With reference to <figref idref="DRAWINGS">FIG. 3C</figref>, illustrated therein is a portion of the system <b>300</b>, including the waste collection apparatus <b>330</b> being cleaned using the cleaning solution <b>324</b>. In particular, as shown in the embodiment of <figref idref="DRAWINGS">FIG. 3C</figref>, the cleaning solution <b>324</b> is sprayed onto the inner surfaces of the cup <b>332</b>, for example by appropriately repositioning the nozzle <b>312</b> into any of a plurality of positions so as to spray an entirety of the interior surfaces of the cup <b>332</b>. In various embodiments, any waste is collected into the drain <b>334</b>.

0028<figref idref="DRAWINGS">FIG. 4</figref> shows an alternative embodiment of the delivery apparatus <b>316</b> and the cleaning thereof. Referring to <figref idref="DRAWINGS">FIG. 4</figref>, the delivery apparatus <b>316</b> does not use a three-way valve. Instead, the containers <b>314</b> and <b>322</b> are switchable and are selectively installed. For example, during spin-coating cycles, the container <b>314</b> is used; during cleaning cycles, the container <b>322</b> replaces the container <b>314</b>. This simplifies the delivery apparatus <b>316</b> and makes it easier to clean. Other embodiments of applying the cleaning solution <b>324</b> are possible. For example, instead of using pressurized gas, a pump can be used to extract the cleaning solution <b>324</b> from the container <b>322</b> into the delivery apparatus <b>316</b>.

0029In various embodiments, the cleaning solution <b>324</b> is a mixture of a basic chemical compound and a solvent, such as an organic solvent. The basic chemical compound is dissolved into the solvent, resulting in a basic cleaning solution <b>324</b> that is rich in hydroxide ions. In various embodiments, the basic cleaning solution <b>324</b> has a high pH value (e.g., greater than about 10). In some embodiments, Si—O bonds, which form the cross-linked structure <b>106</b> (<figref idref="DRAWINGS">FIG. 1</figref>), are not stable at high pH values (e.g., at pH values greater than about 10). Thus, the basic cleaning solution <b>324</b> may be used to break down the Si—O bonds of the silicon-containing material, dissolve the silicon-containing material, and effectively clean the system <b>300</b>. In at least some embodiments, a “silicon-containing material layer” may include a layer having a silicon (Si) concentration greater than about 10%.

0030In an embodiment, the basic chemical compound is tetramethylammonium hydroxide (TMAH) and the solvent is a glycol ether such as propylene glycol ethyl ether (PGEE). In some embodiments, the solvent includes 70% by weight propylene glycol monomethylether (PGME) and 30% by weight propylene glycol monomethylether acetate (PGMEA), such as the solvent OK73, discussed above. In some embodiments, the solvent includes a solution of a solvent and water. For example, in various cases, the solvent solution includes a PGEE/water ratio of about 90/10, 97/3, or 99/1. In some embodiments including a solution of a solvent and water, the water concentration is at least 5% or greater. Thus, in some examples including a solution of PGEE and water, the PGEE/water ratio may be around 95/5. Such a solvent solution may then be mixed with the basic chemical compound (e.g., TMAH) to form the cleaning solution <b>324</b>. In various embodiments, the basic chemical compound may include a 0.24% by weight TMAH solution, a 0.07% by weight TMAH solution, or a 0.02% by weight TMAH solution. In some embodiments, the basic chemical compound includes a 0.20% by weight (or greater) TMAH solution. Other chemicals, such as surfactants and/or additives, may be added to further adjust the pH value and viscosity of the cleaning solution <b>324</b>.

0031For purposes of illustration, in various embodiments and with reference to <figref idref="DRAWINGS">FIG. 5</figref>, unstable Si—O bonds (e.g., at the high pH values of the cleaning solution <b>324</b>) break apart, and hydroxide ions (OH⁻) of the cleaning solution <b>324</b> are effective in replacing the oxygen of the broken Si—O bonds. In various applications, the cleaning solution <b>324</b> can be used to dissolve hardened silicon-containing material <b>310</b> and remove it from the surfaces of the delivery apparatus <b>316</b>, the waste collection apparatus <b>330</b>, and/or other surfaces of the system <b>300</b>. In at least some of the embodiments described herein, the cleaning solution <b>324</b> has a concentration of hydroxide ions (OH⁻) in a range of between about 0.01% and about 10%.

0032Referring now to <figref idref="DRAWINGS">FIG. 6</figref>, a table <b>600</b> illustrated therein shows the effectiveness of some embodiments of the cleaning solution <b>324</b> in removing the silicon-containing material <b>310</b> from a surface of the system <b>300</b>. In the embodiments of <figref idref="DRAWINGS">FIG. 6</figref>, the basic chemical compound is TMAH, and the solvent is PGEE or a solution of PGEE and water. The data in the table <b>600</b> was collected by spin-coating the silicon-containing material <b>310</b> over a substrate (e.g., the substrate <b>304</b>) and letting the silicon-containing material <b>310</b> dry out at room temperature. An initial film thickness (FT) was measured, and the substrate <b>304</b> including a film of the silicon-containing material (e.g., the silicon-containing material layer <b>306</b>) was then submerged into a container holding an embodiment of the cleaning solution <b>324</b> for a plurality of dipping times (e.g., five minutes, two hours, and 12 hours). The thickness of the film was measured again after dipping the substrate <b>304</b> into the cleaning solution <b>324</b>. It is noted that the data of the table <b>600</b> may also be used to calculate an etch rate for various embodiments of the cleaning solution <b>324</b>.

0033As shown in <figref idref="DRAWINGS">FIG. 6</figref>, the table <b>600</b> shows the initial FT <b>602</b> (425 Angstroms, also represented as 100% FT), and the measured FT after a five minute cleaning solution dip <b>604</b>, after a two hour cleaning solution dip <b>606</b>, and after a 12 hour cleaning solution dip <b>608</b>. The experiment illustrated in <figref idref="DRAWINGS">FIG. 6</figref> was performed for a plurality of embodiments of the cleaning solution <b>324</b>. In a first embodiment <b>610</b>, the cleaning solution <b>324</b> includes only PGEE. In a second embodiment <b>612</b>, the cleaning solution <b>324</b> includes a 0.02% by weight TMAH solution mixed with a solvent solution including a PGEE/water ratio of about 99/1. In a third embodiment <b>614</b>, the cleaning solution <b>324</b> includes a 0.07% by weight TMAH solution mixed with a solvent solution including a PGEE/water ratio of about 97/3. In a fourth embodiment <b>616</b>, the cleaning solution <b>324</b> includes a 0.24% by weight TMAH solution mixed with a solvent solution including a PGEE/water ratio of about 90/10. The efficacy of the various embodiments <b>610</b>, <b>612</b>, <b>614</b>, <b>616</b> is evident by the data of the table <b>600</b>. For the case of the first embodiment <b>610</b>, there is no measurable change in thickness of the film until after 12 hours in the PGEE-only cleaning solution <b>324</b>, where the measured thickness reduced to 415 Angstroms (˜97% of the initial FT). For the example of the second embodiment <b>612</b>, there is no measurable change in thickness of the film until after two hours in the 0.02% TMAH, PGEE/water ratio ˜99/1 cleaning solution <b>324</b>, where the measured thickness reduced to 415 Angstroms (˜97% of the initial FT). The measured thickness did not reduce further, as compared to the two hour measurement, after 12 hours in the second embodiment <b>612</b> of the cleaning solution <b>324</b>. For the example of the third embodiment <b>614</b>, there is no measurable change in thickness of the film until after two hours in the 0.07% TMAH, PGEE/water ratio ˜97/3 cleaning solution <b>324</b>, where the measured thickness reduced to 395 Angstroms (˜93% of the initial FT). After 12 hours in the third embodiment <b>614</b> of the cleaning solution <b>324</b>, the measured thickness was further reduced to 350 Angstroms (˜82% of the initial FT). For the example of the fourth embodiment <b>616</b>, there is a rapid change in thickness of the film until after five minutes in the 0.24% TMAH, PGEE/water ratio ˜90/10 cleaning solution <b>324</b>, where the measured thickness reduced to 35 Angstroms (˜8% of the initial FT). After two hours (and again at 12 hours) in the fourth embodiment <b>616</b> of the cleaning solution <b>324</b>, the measured thickness was further reduced to less than 20 Angstroms (˜0% of the initial FT). In some embodiments, a reduction of the FT to less than 20 Angstroms is considered to be a complete removal of the silicon-containing material <b>310</b>.

0034<figref idref="DRAWINGS">FIGS. 7A and 7B</figref> show a flow chart of a semiconductor manufacturing method <b>700</b>, illustrating some exemplary applications of various embodiments of the cleaning solution <b>324</b>. It is noted that these are merely examples and do not limit where and how the cleaning solution <b>324</b> is used. Additional steps may also be provided before, during, and after the method <b>700</b>, and some steps described can be replaced, eliminated, or moved before or after other steps for additional embodiments of the method. It is also noted that the method <b>700</b> is exemplary, and is not intended to limit the present disclosure beyond what is explicitly recited in the claims that follow. The method <b>700</b> will be further described below in conjunction with <figref idref="DRAWINGS">FIGS. 3A-3C, 4, and 8A-8G</figref>.

0035Referring to <figref idref="DRAWINGS">FIGS. 7A and 8A</figref>, the method <b>700</b> begins at block <b>702</b> where a substrate <b>802</b>, used to fabricate a semiconductor device <b>800</b>, is provided. In various embodiments, the substrate <b>802</b> is a semiconductor wafer, such as a silicon wafer. Additionally, in some embodiments, the substrate <b>802</b> may include various layers, including conductive or insulating layers formed on a semiconductor substrate. The substrate <b>802</b> may further include various doping configurations depending on design requirements as is known in the art. The substrate <b>802</b> may also include other semiconductors such as germanium, silicon carbide (SiC), silicon germanium (SiGe), or diamond. Alternatively, the substrate <b>802</b> may include a compound semiconductor and/or an alloy semiconductor. Further, the substrate <b>802</b> may optionally include an epitaxial layer (epi-layer), may be strained for performance enhancement, may include a silicon-on-insulator (SOI) structure, and/or have other suitable enhancement features. Also shown in <figref idref="DRAWINGS">FIG. 8A</figref>, the device <b>800</b> further includes a BARC layer <b>804</b> formed over the substrate <b>802</b> as the bottom layer of a tri-layer lithographic stack. In an embodiment, the BARC layer <b>804</b> is formed using a spin-coating process such as illustrated in <figref idref="DRAWINGS">FIG. 3A</figref>, followed by a baking process.

0036Referring to <figref idref="DRAWINGS">FIGS. 3A, 7A and 8B</figref>, the method <b>700</b> proceeds to block <b>704</b> where a silicon-containing material <b>310</b> is dispensed over the BARC layer <b>504</b> to form a silicon-containing material layer <b>806</b>. In an embodiment, the dispensing of the silicon-containing material <b>310</b> is performed using a spin-coating process such as illustrated in <figref idref="DRAWINGS">FIG. 3A</figref>. To further this embodiment, the silicon-containing material <b>310</b> may be delivered through a delivery apparatus <b>316</b> including a pipeline <b>318</b> and dispensed onto the device <b>800</b> through a nozzle <b>312</b> (<figref idref="DRAWINGS">FIG. 3A</figref>). By way of example, the device <b>800</b> including the substrate <b>802</b> and the BARC layer <b>804</b> is secured on a substrate stage, such as the substrate stage <b>302</b>, and spun at a certain speed while the silicon-containing material <b>310</b> is dispensed. A thickness of the silicon-containing material layer <b>806</b> may be controlled by the spin speed, the dispensing flow rate, the dispensing time, and other factors. In an embodiment, block <b>704</b> further includes collecting chemical waste derived from the silicon-containing material <b>310</b> into a collection apparatus <b>330</b> which includes a collection cup <b>332</b> and a drain <b>334</b> (<figref idref="DRAWINGS">FIG. 3A</figref>). It is noted that in an embodiment of block <b>704</b>, the dispensed silicon-containing material <b>310</b> may also be dispensed onto surfaces of the delivery apparatus <b>316</b>, the waste collection apparatus <b>330</b>, and/or other surfaces of the system <b>300</b>, thereby forming a hardened layer of silicon-containing material <b>310</b> upon such surfaces. As described in more detail below, a cleaning solution (e.g., the cleaning solution <b>324</b>) may be used to remove such hardened layers of silicon-containing material <b>310</b> from any of a plurality of surfaces of the system <b>300</b>. The method <b>700</b> proceeds to block <b>706</b> where after the silicon-containing material layer <b>806</b> has been formed over the BARC layer <b>804</b>, the device <b>800</b> is moved to other processing units for further processes. This will be discussed in more detail below with respect to <figref idref="DRAWINGS">FIG. 7B</figref>.

0037The method <b>700</b> proceeds to block <b>708</b> where a cleaning solution is provided. In an embodiment, the provided cleaning solution is the cleaning solution <b>324</b> described above which is formed by mixing a basic chemical compound with a solvent, such as an organic solvent. In an embodiment, the basic chemical compound is TMAH and the solvent includes a solution of solvent and water. In some embodiments, the solvent includes a solution of PGEE and water having a PGEE/water ratio of about 90/10, 95/5, 97/3, 99/1, or any ratio in between these values. In some embodiments, other solvents such as PGME, PGMEA, OK73, or others known in the art, may be used. In various embodiments, regardless of the solvent used, the water concentration in the solvent/water solution is at least 5%. In some embodiments, the basic chemical compound of the cleaning solution includes a 0.24% by weight TMAH solution, a 0.07% by weight TMAH solution, or a 0.02% by weight TMAH solution. In some embodiments, the basic chemical compound includes a 0.20% by weight (or greater) TMAH solution. In addition, various other chemicals, such as surfactants and/or additives, may be added to adjust the pH value and viscosity of the cleaning solution. Other embodiments of the cleaning solution are possible, as discussed above.

0038The method <b>700</b> proceeds to block <b>710</b> where the delivery apparatus (e.g., the delivery apparatus <b>316</b>) and the waste collection apparatus (e.g., the waste collection apparatus <b>330</b>) are cleaned by dispensing the cleaning solution onto surfaces of the delivery apparatus and the waste collection apparatus. In some embodiments, this includes actuating the three-way valve <b>328</b> such that a flow of the silicon-containing material <b>310</b> is switched off and such that a flow of the cleaning solution <b>324</b> is switched on, as illustrated in <figref idref="DRAWINGS">FIG. 3B</figref>. Alternatively, in some embodiments, this includes replacing a container <b>314</b> that holds the silicon-containing material <b>310</b> with a container <b>322</b> that holds the cleaning solution <b>324</b> as shown in <figref idref="DRAWINGS">FIG. 4</figref>. In various embodiments, the cleaning solution <b>324</b> may be introduced into the delivery apparatus <b>316</b> via a pressurized gas, a pump, or other mechanism.

0039In a further embodiment of block <b>710</b>, elements of the waste collection apparatus, such as the collection cup <b>332</b> and the drain <b>334</b> are cleaned. In an embodiment, the waste collection apparatus <b>330</b> may be cleaned by directly spraying, or otherwise dispensing, the cleaning solution <b>324</b> thereon, as illustrated in <figref idref="DRAWINGS">FIG. 3C</figref>. The basic cleaning solution <b>324</b>, having a high pH value (e.g., greater than about 10), destabilizes the Si—O bonds of the silicon-containing material, thereby effectively removing solidified particles of the silicon-containing material off of the surfaces of the delivery apparatus <b>316</b>, the waste collection apparatus <b>330</b>, and various other components of the system <b>300</b>.

0040Returning to blocks <b>704</b>/<b>706</b>, after the silicon-containing material layer <b>806</b> has been formed over the BARC layer <b>804</b> (block <b>704</b>), the device <b>800</b> is moved to other processing units for further processing (block <b>706</b>). Some embodiments of this further processing are described now with <figref idref="DRAWINGS">FIG. 7B</figref>. In particular, <figref idref="DRAWINGS">FIG. 7B</figref> shows a portion of the method <b>700</b> which describes further processing of the device <b>800</b> and more applications of the cleaning solution <b>324</b>. In some embodiments, and with reference to <figref idref="DRAWINGS">FIGS. 7B and 8B</figref>, after the silicon-containing material layer <b>806</b> has been spin-coated over the BARC layer <b>804</b> and the device <b>800</b> has been moved for further processing, the method <b>700</b> proceeds to block <b>712</b> where the substrate <b>802</b> including the BARC layer <b>804</b> and the silicon-containing material layer <b>806</b> is baked. In some embodiments, the baking operation may take place in another processing unit, such as an oven or furnace, separate from the spin-coating system <b>300</b>. In various embodiments, the baking operation drives solvent out of the silicon-containing material layer <b>806</b> and solidifies the material therein, making it a hard mask layer <b>806</b> (<figref idref="DRAWINGS">FIG. 8B</figref>) for subsequent etching processes. In some embodiments, drying out of the solvent, for example by the baking process, serves to initiate the cross-linking process described above.

0041The method <b>700</b> proceeds to block <b>714</b> where the baked silicon-containing material layer <b>806</b> (i.e., the hard mask layer <b>806</b>) is patterned. In some examples, patterning the hard mask layer <b>806</b> includes multiple steps, as illustrated in <figref idref="DRAWINGS">FIGS. 8C and 8D</figref>. Referring to <figref idref="DRAWINGS">FIG. 8C</figref>, in an embodiment of block <b>714</b>, a resist layer <b>808</b> is formed over the hard mask layer <b>806</b>, the resist layer <b>808</b> is exposed to radiation <b>812</b> through a mask (or photo-mask or reticle) <b>810</b>, and the exposed resist layer <b>808</b> is developed to form a patterned resist layer. In various embodiments, the resist layer <b>808</b> may be a positive resist or a negative resist. A positive resist is normally insoluble in a resist developer, but is made soluble by exposure to the radiation. A negative resist has the opposite behavior. By way of example, the mask <b>810</b> may include an IC design layout pattern to be formed on the device <b>800</b>. The radiation <b>812</b> may include deep ultraviolet (DUV) radiation, extreme ultraviolet (EUV) radiation, an electron beam (e-beam), or other suitable radiation. Referring to <figref idref="DRAWINGS">FIG. 8D</figref>, block <b>714</b> further includes etching the hard mask layer <b>806</b> with the patterned resist layer acting as an etch mask and subsequently removing the patterned resist layer, resulting in a patterned hard mask layer <b>806</b>A over the BARC layer <b>804</b>.

0042The method <b>700</b> proceeds to block <b>716</b> where the BARC layer <b>804</b> and/or the substrate <b>802</b> are etched using the patterned hard mask layer <b>806</b>A as an etch mask. Referring to <figref idref="DRAWINGS">FIG. 8E</figref>, in an embodiment of block <b>716</b>, the BARC layer <b>804</b> and/or the substrate <b>802</b> may be etched using a wet etching process, a dry etching process, or other suitable etching processes. In some embodiments, an anisotropic dry etching process may be used to etch the BARC layer <b>804</b> (e.g., to form a patterned BARC layer <b>804</b>A) and/or the substrate <b>802</b> to minimize dimension variations in pattern transfer from the patterned hard mask layer <b>806</b>A to the underlying layers.

0043The method <b>700</b> proceeds to block <b>718</b> where a cleaning solution is provided. In various embodiments, the provided cleaning solution is the cleaning solution <b>324</b> described above which is formed by mixing a basic chemical compound with a solvent, such as an organic solvent. In some embodiments, the provided cleaning solution is the cleaning solution described above with reference to block <b>708</b>. Other embodiments of the cleaning solution are possible, as discussed above.

0044The method <b>700</b> proceeds to block <b>720</b> where the patterned hard mask layer <b>806</b>A is removed with the cleaning solution <b>324</b>. In the embodiment as shown in <figref idref="DRAWINGS">FIG. 8F</figref>, the cleaning solution <b>324</b> is applied to the device <b>800</b> in a wet etching process. Due to various properties discussed above, the cleaning solution <b>324</b> is effective in removing the patterned hard mask layer <b>806</b>A from the substrate <b>802</b> (<figref idref="DRAWINGS">FIG. 8G</figref>). Alternatively, in some embodiments, the patterned hard mask layer <b>806</b>A may be removed using a dry etching process.

0045As discussed above, additional steps may also be provided before, during, and after the method <b>700</b>, and some steps described can be replaced, eliminated, or moved before or after other steps for additional embodiments of the method. For example, in some embodiments, just the delivery apparatus and the waste collection apparatus are cleaned using the cleaning solution, while cleaning the substrate using the cleaning solution (e.g., removing the hard mask layer) is omitted. Alternatively, in some embodiments, the substrate is cleaned using the cleaning solution (i.e., the hard mask layer is removed), while cleaning the spin-coating system (e.g., the delivery apparatus and the waste collection apparatus) using the cleaning solution is omitted. In some examples, both the spin-coating system and the substrate are cleaned using the cleaning solution. In some cases, any semiconductor processing equipment that stores, delivers, or otherwise comes in contact with a silicon-containing material may be cleaned by an embodiment of the cleaning solution described herein. Those of ordinary skill in the art will recognize other embodiments and applications of the cleaning solution, without departing from the scope of the present disclosure.

0046The embodiments of the present disclosure offer advantages over existing art, though it is understood that other embodiments may offer different advantages, not all advantages are necessarily discussed herein, and that no particular advantage is required for all embodiments. By the disclosed cleaning solution composition and the methods of applying the same, the semiconductor spin-coating system can be cleaned effectively. Particularly, various apparatuses handling silicon-containing resist materials can be cleaned without being taken out of the spin-coating system. In addition, spin-coating delivery apparatuses and waste collection apparatuses can be cleaned with the disclosed cleaning solution so that they may avoid becoming clogged. A clean spin-coating system also reduces a potential for contamination of wafers by particles of the silicon-containing resist material. Those of skill in the art will readily appreciate that the methods and cleaning compositions described herein may be applied to a variety of other semiconductor devices and semiconductor processes to advantageously achieve similar benefits to those described herein without departing from the scope of the present disclosure.

0047Thus, one of the embodiments of the present disclosure described a method for fabricating a semiconductor device including coating a surface, which may include a surface of a spin-coating system or a surface of a semiconductor substrate, with a silicon-containing material layer having a first pH value. In various embodiments, a cleaning solution is provided to clean the coated surface, where the cleaning solution includes a basic chemical compound mixed with a solvent solution. In some examples, the cleaning solution has a second pH value greater than the first pH value, and the silicon-containing material layer is unstable at the second pH value. In some embodiments, the cleaning solution is applied to the coated surface, and the cleaning solution dissolves the silicon-containing material layer from the coated surface.

0048In another of the embodiments, discussed is a method for fabricating a semiconductor device including securing a substrate on a substrate stage. In some embodiments, while spinning the substrate stage and the substrate secured thereon, a silicon-containing material is dispensed on the substrate, where the dispensing also dispenses the silicon-containing material onto a surface of a spin-coating system and forms a silicon-containing material layer on the surface of the spin-coating system. In various embodiments, after forming the silicon-containing material layer, a cleaning solution is dispensed onto the silicon-containing material layer, where the cleaning solution includes a basic chemical compound mixed with a solvent solution, and where the cleaning solution has a pH value at which the silicon-containing material layer is unstable. In various examples, responsive to dispensing the cleaning solution onto the silicon-containing material layer, the silicon-containing material layer is removed from the surface of the spin-coating system.

0049In yet other embodiments, discussed is a method including providing a substrate including a first layer disposed over the substrate. In some embodiments, a second layer is formed over the first layer, where the second layer includes a silicon-containing material layer having a silicon concentration greater than about 10%. In various examples, the substrate including the first and second layers is baked, where the baked second layer forms a hard mask layer. In some embodiments, the hard mask layer is patterned and the first layer is etched using the patterned hard mask layer. In some examples, a cleaning solution is dispensed onto the hard mask layer, where the cleaning solution includes a basic chemical compound mixed with a solvent solution, and where the cleaning solution has a pH value at which the hard mask layer is unstable. In various cases, responsive to dispensing the cleaning solution onto the hard mask layer, the hard mask layer is dissolved.

0050The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.